[22] Generate Parentheses

https://leetcode.com/problems/generate-parentheses/description/

• algorithms
• Medium (50.13%)
• Source Code: 22.generate-parentheses.py
• Total Accepted: 245.2K
• Total Submissions: 489K
• Testcase Example: '3'

Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses.

For example, given n = 3, a solution set is:

[ "((()))", "(()())", "(())()", "()(())", "()()()" ]

class Solution(object):
    def generateParenthesis(self, n):
        """
        :type n: int
        :rtype: List[str]
        """